Serious kidney disease, involving substantial impairment of function, affects approximately 3.5 million Americans. Quantitative measurement of regional and global renal perfusion can provide important diagnostic information in the evaluation of such patients. Despite an intense search within the research community for a suitable non-invasive method for such measurements, existing techniques have severe limitations including lack of quantification (MRI), dependence on highly skilled users (color Doppler) or inappropriateness for use in humans (radiolabeled microspheres). Although global kidney function can be assessed using clearance indicators, these techniques provide no direct perfusion information. With a suitable radioactive agent, PET imaging can provide absolute quantification of regional blood flow with excellent spatial resolution and can be applied conveniently in humans. We propose to employ the PET agent 62Cu-ETS for this unique renal application. This agent has a short 9.7minute physical half-life, permitting safe, repeated use in humans and can be nationally distributed through use of a PTI developed generator. In our Phase I studies, this agent has demonstrated uniquely high renal uptake in humans and also demonstrated linear uptake to very high renal flow levels in a pig model. The proposed Phase II work will involve refinement of the radiochemical process for clinical production of the 62Cu-ETS and the necessary work for submission of an Investigational New Drug Application. In addition we will continue our work in Phase I by validating the application of 62Cu-ETS for PET quantification of regional renal perfusion in a pig model of acute focal renal injury, as well as translating the model to 62Cu-ETS quantification of regional renal perfusion in humans. Given the strength of PET and the characteristics of the Cu-ETS tracer, this imaging procedure can provide an ideal non-invasive technique for absolute quantitative measurement of both regional and global renal blood flow with far-reaching benefits in patient management and diagnosis.